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Biomedical subjects

M Smith

Publications and source records attributed to M Smith.

At least 1,009 records · Page 56Linked to original sources
PubMed1987

Oligonucleotide-directed mutagenesis: a simple method using two oligonucleotide primers and a single-stranded DNA template.

The important features of the protocol described here are as follows: First, the procedure consists of a few simple steps and results in a reasonably high frequency of mutagenesis. Second, using two primers, there is no need to isolate covalently closed double-stranded molecules as in our previous method. Third, the use of vectors derived from single-stranded phage facilitates template preparation, mutagenesis efficiency, screening, and DNA sequencing. Fourth, the same basic steps can be directly applied when using the single-stranded pUC derivatives.

Base Sequence↗
PubMed1987

Multifocal static creamy choroidal infiltrates. An early sign of lymphoid neoplasia.

Three patients, each more than 60 years of age at initial presentation, had early stage lymphoid infiltrates (formerly called reactive lymphoid hyperplasia) of the choroid and contiguous extraocular tissues. There were multifocal, confluent, and nonconfluent creamy patches in the choroid. These lesions changed very little over periods of observation ranging from 1 to 4 years and failed to produce ophthalmoscopically visible disturbances of the retinal pigment epithelium (RPE). Fluorescein angiography demonstrated dye collection within the lesions without leakage into the subretinal or subpigment epithelial spaces. Both ultrasonography and computed tomography (CT) showed thickening of the choroid with either anterior or posterior episcleral extensions of lymphoid tissue. Pathologic evaluation of biopsy specimens of extraocular portions of the lesions showed low-grade tumors that were diffuse infiltrates of mature lymphocytes, which exhibited lymphoplasmacytoid features, Dutcher bodies, or small residual germinal centers (so-called borderline lesions). Two patients had uniocular localized disease, whereas the third had bilateral ocular lesions, hypogammaglobulinemia, and another extranodal chest wall lymphoid tumor. Therapy for the localized ocular condition consisted either of oral administration of corticosteroids or low doses of radiotherapy.

Aged↗
PubMed1987

Modified new approaches for rapid intravenous access.

We studied the venous system at the groin, ankle, and antecubital area in relationship to easily palpable or visible surface landmarks, and developed new approaches or modifications of existing approaches to localize the saphenous vein at the groin, ankle, and the basilic vein in the antecubital area. A prospective crossover study comparing these new cutdown techniques with the most commonly described traditional techniques was performed, using inexperienced medical personnel. They were divided into two groups, and the average time to successful venous isolation with each method at each of the three sites was studied. Both groups were similar in that all participants were medical personnel (interns, flight nurses, an equal number in each group) who had not previously performed venous cutdowns. In each group, at all sites, the new cutdown techniques resulted in a more rapid isolation of the vein. This was true in each case regardless of which technique was learned and attempted first.

Ankle↗
PubMed1987

Contrast echo washout curves from the left ventricle: application of basic principles of indicator-dilution theory and calculation of ejection fraction.

Time-intensity curves can be obtained from contrast echocardiography of the left ventricle. The purposes of this study were: 1) to verify whether these curves conform to the basic principles of indicator-dilution theory; and 2) to derive indexes of left ventricular ejection fraction from curve analysis. In seven closed chest dogs, 31 doses of the polysaccharide agent SHU-454 were injected into the left ventricular cavity during apical four chamber two-dimensional echocardiography. Data were obtained at different levels of ejection fraction, which were induced by changes in preload, afterload and contractility, and measured by single plane Simpson's rule analysis of digital subtraction left ventriculograms. In a subset of two dogs, eight incremental doses (from 1 to 8 ml) of SHU were injected in the basal state. Contrast echocardiograms were digitized off-line, the mean gray level/pixel of a region of interest inside the left ventricular cavity was measured, and the average value for three systolic frames of each beat was used to obtain time-intensity curves. A good correlation was observed between the peak of the time-intensity curve and the quantity of contrast injected (correlation coefficient r = 0.91 by a logarithmic fit). The echo intensities observed in each animal were subsequently transformed in quantity of contrast according to these functions and their natural logarithm was calculated both with and without background subtraction. All curves relating time and the natural logarithm of the corrected intensity exhibited a descending rectilinear portion (washout) in which the correlation was very good (r = 0.97 +/- 0.02 = mean +/- SD) and which was not significantly affected by background subtraction. The validity of this fit was also unaffected by heart rate (55 to 158 beats/min) and angiographic ejection fraction (22 to 74%), and only minimally influenced by duration of contrast washout (3.3 to 14.6 seconds). Ejection fraction was calculated by an algorithm derived from indicator-dilution theory: ejection fraction = [1 - e(-bd)] X 100, where b = slope of the curve and d = cardiac cycle duration. Linear regression analysis between values of ejection fraction derived by angiography and contrast echo yielded r = 0.73. A second index, based on b and d, was derived by multiple regression analysis. Linear regression analysis of this index and angiographic ejection fraction yielded a correlation of r = 0.87.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Yeast cytochrome c with phenylalanine or tyrosine at position 87 transfers electrons to (zinc cytochrome c peroxidase)+ at a rate ten thousand times that of the serine-87 or glycine-87 variants.

Of the many factors known to influence the rate of electron transfer between two metalloproteins, it is particularly difficult to assess the role of the polypeptide matrix intervening between the donor and acceptor sites. To determine whether the phylogenetically conserved Phe-87 of yeast iso-1-cytochrome c helps to mediate electron transfer between cytochrome c and cytochrome c peroxidase, we have constructed mutants of cytochrome c that are altered at this position and now have studied the kinetics of long-range electron transfer within their complexes with zinc-substituted cytochrome c peroxidase. We find that the rate of electron transfer from reduced cytochrome c to the zinc cytochrome c peroxidase pi-cation radical is four orders of magnitude greater when phenylalanine or tyrosine is present at position 87 than when serine or glycine is present.

Cytochrome c Group↗
PubMed1987

Increased number of mast cells in the dominant follicle of the cow: relationships among luteal, stromal, and hilar regions.

The number of mast cells per microscopic field at 450X (0.123 mm2) was determined in the bovine ovary on Days 4, 10, and 19 of the cycle (Day 0 = estrus). Mast cells were observed in the theca externa of follicles, the external capsule of the corpus luteum, and in the stromal and hilar regions of the ovary. The stromal and hilar regions exhibited the highest number of mast cells (per field = 7.51-10.15) compared with the follicular and luteal compartments (2.65-3.70 mast cells/field). Most interestingly, on Day 19 a significant increase in the number of mast cells was observed in the theca externa of the dominant follicle (10.4 mast cells/field) compared with nondominant healthy follicles on Days 4 and 10 (2-3/field). After ovulation, the number of mast cells surrounding the corpus luteum on Day 4 was significantly lower than 19 values in the dominant follicle; this was further diminished on Day 10 of the cycle. These results indicate that the increase in mast cells associated with the dominant follicle on Day 19 may be related to its development and the decline in mast cells related to ovulation.

Animals↗
PubMed1987

Splenic platelet-sequestration following routine blood transfusion is reduced by filtered/washed blood products.

The mean fall in the platelet count following 23 routine transfusions of 3-5 units packed cells for anaemia was 32.5%. This was significantly reduced to 12.5% in 15 similar transfusions through a 40 microns microaggregate filter (P less than 0.01) and to 4.6% following five transfusions through a polyester fibre filter (P less than 0.005). In 10 transfusions with frozen or polyester fibre filtered, washed red cells, the decrease in platelet count was 4.2% (P less than 0.001). A study of 111In-oxine labelled autologous platelets in nine patients indicated that the fall in platelet count was due to increased splenic sequestration. Since thrombocytopenia following routine transfusion is reduced by procedures which filter the packed cells, the decrease in platelets is probably caused by their adherence to infused microaggregate debris causing their premature removal from the circulation. Patients with preexisting thrombocytopenia who receive red cell transfusions for anaemia, should therefore receive blood products depleted of microaggregate debris in order to avoid exacerbation of thrombocytopenia and haemorrhagic complications.

Anemia↗
PubMed1987

Neurochemical characteristics of a novel dorsal root ganglion X neuroblastoma hybrid cell line, F-11.

We investigated the properties of the novel dorsal root ganglion (DRG) hybrid cell line F-11 to see how closely these cells resembled normal DRG cells. Under normal growth conditions, F-11 cells appeared to contain several short neurite-like processes. However, these cells could also be grown under conditions in which they showed a much more extensive neuronal morphology, exhibiting many long neurites. Several differentiated features of DRG cells were present on F-11 cells. These included the presence of delta-opioid receptors, receptors for prostaglandins and bradykinin, and dihydropyridine-sensitive calcium channels. F-11 cells also synthesized and released a substance P-like compound, as determined by immunoreactivity. Both the number of bradykinin receptors and the voltage-sensitive calcium influx increased on cell differentiation. Opioid agonists (delta-specificity) were found to decrease cyclic AMP levels in F-11 cells in a naloxone- and pertussis toxin-reversible fashion. Bradykinin stimulated the synthesis of inositol-1,4-bisphosphate and inositol-1,4,5-trisphosphate. Ca2+ channel agonists stimulated voltage-sensitive Ca2+ influx in a dose-dependent, stereospecific manner, whereas Ca2+ channel antagonists inhibited Ca2+ influx. F-11 cells should, therefore, prove useful as models for authentic DRG neurons.

Animals↗
PubMed1987

Effect of food on enoxacin absorption.

Fifteen subjects received a single 400-mg oral dose of enoxacin in the fasting state and after carbohydrate and high-fat meals. The carbohydrate meal delayed the time to peak enoxacin concentration in plasma by an average of 0.92 h. The extent of enoxacin absorption was not altered by food.

Administration, Oral↗
PubMed1987

Synergism of platelet-aggregating agents. Role of elevation of cytoplasmic calcium.

When a pair of platelet agonists, each in subthreshold concentration, is added together or in sequence to a platelet suspension, the platelet response is enhanced. Addition of two agonists to platelets loaded with aequorin also enhanced the observed rise in cytoplasmic ionized calcium ([Ca2+]i) in response to the second agonist if the agonists were added within 20 s of each other. Enhancement of aggregation and secretion required that an increase in [Ca2+]i (as indicated by aequorin but not necessarily indo-1) followed the first agonist, but not that the [Ca2+]i remain elevated until addition of the second agonist. Enhancement was not prevented by aspirin, ADP scavengers, or chelators of extracellular Ca2+. We conclude that a rise in [Ca2+]i induced by a first agonist "primes" platelets for an augmented functional response to a second agonist, which is not, however, determined by the [Ca2+]i at the time of addition of the second agonist.

Adenosine Diphosphate↗
PubMed1987

Patient attrition in dynamically oriented treatment groups.

Clinical and empirical studies of premature terminators from dynamically oriented therapy groups are reviewed. While many studies focus on the personality characteristics of dropouts, the authors recommend conceptualizing such patients in terms of the interaction of patient, group, and therapist. On the basis of this model, the authors offer clinical recommendations for reducing the number of dropouts. Multivariate experimental designs for studying attrition in group psychotherapy are discussed, and the authors suggest possible directions for future research.

Attitude of Health Personnel↗
PubMed1987

Aminoglycoside monitoring: use of a pharmacokinetic service versus physician recommendations.

Two patient populations were evaluated regarding the monitoring of aminoglycoside serum concentrations by either a pharmacokinetic service (PKS) or staff physicians. Both groups were evenly matched by demographic characteristics, underlying disease state(s), and indication for aminoglycoside therapy. Patients in the PKS group showed increased incidence of clinical improvement after therapy when compared with the physicians' group; a decreased length of stay and duration of treatment were also observed in this group. Aminoglycoside dosing and monitoring by the PKS provided an estimated average cost savings of $491,00 per patient. The results indicate that the PKS may provide cost savings and benefit in aminoglycoside monitoring for the patient and/or the hospital.

Adolescent↗
PubMed1987

Use of intravenous pyelography in blunt trauma--a reappraisal.

The role of intravenous pyelography (IVP) in the evaluation of blunt abdominal trauma is controversial. Major renal injuries have occasionally been reported in the absence of hematuria, but the test is not always accurate, is expensive and has potential morbidity. By reviewing the charts of 150 consecutive patients seen in an emergency department who had IVP for blunt abdominal trauma, we evaluated the ability of clinical and laboratory findings to predict IVP findings, the incidence of abnormal findings on IVP and the number of times IVP affected patient management. Only one patient's management was found to be clearly affected by the results of the IVP. We feel, therefore, that IVP should be reserved in cases of blunt abdominal trauma for patients with gross hematuria and those with microscopic hematuria and suggestive clinical findings. The absence of hematuria should preclude the use of IVP unless there are other exceedingly strong clinical findings.

Abdominal Injuries↗